package services

import (
	"context"

	"github.com/breakpilot/school-service/internal/models"
	"github.com/jackc/pgx/v5/pgxpool"
)

// TimetableService handles all CRUD for the school-wide timetable scheduler:
// classes, periods, rooms, subjects, teachers, curriculum, assignments.
type TimetableService struct {
	db *pgxpool.Pool
}

func NewTimetableService(db *pgxpool.Pool) *TimetableService {
	return &TimetableService{db: db}
}

// ---------- Classes ----------

func (s *TimetableService) CreateClass(ctx context.Context, userID string, req *models.CreateTimetableClassRequest) (*models.TimetableClass, error) {
	var c models.TimetableClass
	err := s.db.QueryRow(ctx, `
		INSERT INTO tt_class (created_by_user_id, name, grade_level, student_count, notes)
		VALUES ($1, $2, $3, $4, $5)
		RETURNING id, created_by_user_id, name, grade_level, student_count, notes, created_at
	`, userID, req.Name, req.GradeLevel, req.StudentCount, req.Notes).Scan(
		&c.ID, &c.CreatedByUserID, &c.Name, &c.GradeLevel, &c.StudentCount, &c.Notes, &c.CreatedAt,
	)
	return &c, err
}

func (s *TimetableService) ListClasses(ctx context.Context, userID string) ([]models.TimetableClass, error) {
	rows, err := s.db.Query(ctx, `
		SELECT id, created_by_user_id, name, grade_level, student_count, COALESCE(notes,''), created_at
		FROM tt_class WHERE created_by_user_id = $1 ORDER BY grade_level, name
	`, userID)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	var out []models.TimetableClass
	for rows.Next() {
		var c models.TimetableClass
		if err := rows.Scan(&c.ID, &c.CreatedByUserID, &c.Name, &c.GradeLevel, &c.StudentCount, &c.Notes, &c.CreatedAt); err != nil {
			return nil, err
		}
		out = append(out, c)
	}
	return out, nil
}

func (s *TimetableService) DeleteClass(ctx context.Context, id, userID string) error {
	_, err := s.db.Exec(ctx, `DELETE FROM tt_class WHERE id = $1 AND created_by_user_id = $2`, id, userID)
	return err
}

// ---------- Periods ----------

func (s *TimetableService) CreatePeriod(ctx context.Context, userID string, req *models.CreateTimetablePeriodRequest) (*models.TimetablePeriod, error) {
	var p models.TimetablePeriod
	err := s.db.QueryRow(ctx, `
		INSERT INTO tt_period (created_by_user_id, day_of_week, period_index, start_time, end_time, is_break, label)
		VALUES ($1, $2, $3, $4, $5, $6, $7)
		RETURNING id, created_by_user_id, day_of_week, period_index, start_time::text, end_time::text, is_break, COALESCE(label,''), created_at
	`, userID, req.DayOfWeek, req.PeriodIndex, req.StartTime, req.EndTime, req.IsBreak, req.Label).Scan(
		&p.ID, &p.CreatedByUserID, &p.DayOfWeek, &p.PeriodIndex, &p.StartTime, &p.EndTime, &p.IsBreak, &p.Label, &p.CreatedAt,
	)
	return &p, err
}

func (s *TimetableService) ListPeriods(ctx context.Context, userID string) ([]models.TimetablePeriod, error) {
	rows, err := s.db.Query(ctx, `
		SELECT id, created_by_user_id, day_of_week, period_index, start_time::text, end_time::text, is_break, COALESCE(label,''), created_at
		FROM tt_period WHERE created_by_user_id = $1 ORDER BY day_of_week, period_index
	`, userID)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	var out []models.TimetablePeriod
	for rows.Next() {
		var p models.TimetablePeriod
		if err := rows.Scan(&p.ID, &p.CreatedByUserID, &p.DayOfWeek, &p.PeriodIndex, &p.StartTime, &p.EndTime, &p.IsBreak, &p.Label, &p.CreatedAt); err != nil {
			return nil, err
		}
		out = append(out, p)
	}
	return out, nil
}

func (s *TimetableService) DeletePeriod(ctx context.Context, id, userID string) error {
	_, err := s.db.Exec(ctx, `DELETE FROM tt_period WHERE id = $1 AND created_by_user_id = $2`, id, userID)
	return err
}

// ---------- Rooms ----------

func (s *TimetableService) CreateRoom(ctx context.Context, userID string, req *models.CreateTimetableRoomRequest) (*models.TimetableRoom, error) {
	var r models.TimetableRoom
	err := s.db.QueryRow(ctx, `
		INSERT INTO tt_room (created_by_user_id, name, room_type, capacity, floor_level, has_elevator, notes)
		VALUES ($1, $2, $3, $4, $5, $6, $7)
		RETURNING id, created_by_user_id, name, COALESCE(room_type,''), capacity, floor_level, has_elevator, COALESCE(notes,''), created_at
	`, userID, req.Name, req.RoomType, req.Capacity, req.FloorLevel, req.HasElevator, req.Notes).Scan(
		&r.ID, &r.CreatedByUserID, &r.Name, &r.RoomType, &r.Capacity, &r.FloorLevel, &r.HasElevator, &r.Notes, &r.CreatedAt,
	)
	return &r, err
}

func (s *TimetableService) ListRooms(ctx context.Context, userID string) ([]models.TimetableRoom, error) {
	rows, err := s.db.Query(ctx, `
		SELECT id, created_by_user_id, name, COALESCE(room_type,''), capacity, floor_level, has_elevator, COALESCE(notes,''), created_at
		FROM tt_room WHERE created_by_user_id = $1 ORDER BY name
	`, userID)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	var out []models.TimetableRoom
	for rows.Next() {
		var r models.TimetableRoom
		if err := rows.Scan(&r.ID, &r.CreatedByUserID, &r.Name, &r.RoomType, &r.Capacity, &r.FloorLevel, &r.HasElevator, &r.Notes, &r.CreatedAt); err != nil {
			return nil, err
		}
		out = append(out, r)
	}
	return out, nil
}

func (s *TimetableService) DeleteRoom(ctx context.Context, id, userID string) error {
	_, err := s.db.Exec(ctx, `DELETE FROM tt_room WHERE id = $1 AND created_by_user_id = $2`, id, userID)
	return err
}

// ---------- Subjects ----------

func (s *TimetableService) CreateSubject(ctx context.Context, userID string, req *models.CreateTimetableSubjectRequest) (*models.TimetableSubject, error) {
	var sub models.TimetableSubject
	err := s.db.QueryRow(ctx, `
		INSERT INTO tt_subject (created_by_user_id, name, short_code, color, is_main_subject, required_room_type)
		VALUES ($1, $2, $3, $4, $5, $6)
		RETURNING id, created_by_user_id, name, short_code, COALESCE(color,''), is_main_subject, COALESCE(required_room_type,''), created_at
	`, userID, req.Name, req.ShortCode, req.Color, req.IsMainSubject, req.RequiredRoomType).Scan(
		&sub.ID, &sub.CreatedByUserID, &sub.Name, &sub.ShortCode, &sub.Color, &sub.IsMainSubject, &sub.RequiredRoomType, &sub.CreatedAt,
	)
	return &sub, err
}

func (s *TimetableService) ListSubjects(ctx context.Context, userID string) ([]models.TimetableSubject, error) {
	rows, err := s.db.Query(ctx, `
		SELECT id, created_by_user_id, name, short_code, COALESCE(color,''), is_main_subject, COALESCE(required_room_type,''), created_at
		FROM tt_subject WHERE created_by_user_id = $1 ORDER BY name
	`, userID)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	var out []models.TimetableSubject
	for rows.Next() {
		var sub models.TimetableSubject
		if err := rows.Scan(&sub.ID, &sub.CreatedByUserID, &sub.Name, &sub.ShortCode, &sub.Color, &sub.IsMainSubject, &sub.RequiredRoomType, &sub.CreatedAt); err != nil {
			return nil, err
		}
		out = append(out, sub)
	}
	return out, nil
}

func (s *TimetableService) DeleteSubject(ctx context.Context, id, userID string) error {
	_, err := s.db.Exec(ctx, `DELETE FROM tt_subject WHERE id = $1 AND created_by_user_id = $2`, id, userID)
	return err
}

// ---------- Teachers ----------

func (s *TimetableService) CreateTeacher(ctx context.Context, userID string, req *models.CreateTimetableTeacherRequest) (*models.TimetableTeacher, error) {
	var t models.TimetableTeacher
	err := s.db.QueryRow(ctx, `
		INSERT INTO tt_teacher (created_by_user_id, first_name, last_name, short_code, employment_percentage, max_hours_week, notes)
		VALUES ($1, $2, $3, $4, $5, $6, $7)
		RETURNING id, created_by_user_id, first_name, last_name, short_code, employment_percentage, max_hours_week, COALESCE(notes,''), created_at
	`, userID, req.FirstName, req.LastName, req.ShortCode, req.EmploymentPercentage, req.MaxHoursWeek, req.Notes).Scan(
		&t.ID, &t.CreatedByUserID, &t.FirstName, &t.LastName, &t.ShortCode, &t.EmploymentPercentage, &t.MaxHoursWeek, &t.Notes, &t.CreatedAt,
	)
	return &t, err
}

func (s *TimetableService) ListTeachers(ctx context.Context, userID string) ([]models.TimetableTeacher, error) {
	rows, err := s.db.Query(ctx, `
		SELECT id, created_by_user_id, first_name, last_name, short_code, employment_percentage, max_hours_week, COALESCE(notes,''), created_at
		FROM tt_teacher WHERE created_by_user_id = $1 ORDER BY last_name, first_name
	`, userID)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	var out []models.TimetableTeacher
	for rows.Next() {
		var t models.TimetableTeacher
		if err := rows.Scan(&t.ID, &t.CreatedByUserID, &t.FirstName, &t.LastName, &t.ShortCode, &t.EmploymentPercentage, &t.MaxHoursWeek, &t.Notes, &t.CreatedAt); err != nil {
			return nil, err
		}
		out = append(out, t)
	}
	return out, nil
}

func (s *TimetableService) DeleteTeacher(ctx context.Context, id, userID string) error {
	_, err := s.db.Exec(ctx, `DELETE FROM tt_teacher WHERE id = $1 AND created_by_user_id = $2`, id, userID)
	return err
}